Solve for each system 6x+6z=66 and x + 7z = 17

6x+6z=66

6x-6x+6z=66-6x

6z=66-6x

6z/6=66-6x/6

z=11-x

x + 7z = 17

x + 7(11-x) = 17

x + 7(11) (7)(-x) = 17

x+77-7x=17

77-6x=17

77-6x-77=17-77

-6x=-60

-6x/-6=-60/-6

x=10

z=11-x

z=11-10=1